ABB Relion 650 Series Technical Manual page 360

Section 11
Scheme communication
CS_STOP
BLOCK
PLTR_CRD
CR
ANSI05000448 V1 EN-US
Figure 190: Simplified logic diagram for blocking scheme
11.4.6.2 Permissive under/overreaching scheme
In the permissive scheme the forward directed ground-fault measuring element sends a
permissive signal to the other end, if a ground fault is detected in the forward direction. The
directional element at the other line end must wait for a permissive signal before activating a trip
signal. Independent channels must be available for the communication in each direction.
An impedance measuring IED, which works in the same type of permissive mode, with one channel
in each direction, can share the channels with the communication scheme for residual overcurrent
protection. If the impedance measuring IED works in the permissive overreaching mode, common
channels can be used in single line applications. In case of double lines connected to a common
bus at both ends, use common channels only if the ratio Z
source impedance) is about equal at both ends. If the ratio is different, the impedance measuring
and the directional ground-fault current system of the healthy line may detect a fault in different
directions, which could result in unwanted tripping.
Common channels cannot be used when the weak-end infeed function is used in the distance or
ground-fault protection.
In case of an internal ground-fault, the forward directed measuring element operates and sends a
permissive signal to the remote end via the CS output (sent signal). Local tripping is permitted
when the forward direction measuring element operates and a permissive signal is received via
the CR binary input (received signal).
The permissive scheme can be of either underreaching or overreaching type. In the underreaching
alternative, an underreaching directional residual overcurrent measurement element will be used
as sending criterion of the permissive input signal CSUR.
In the overreaching alternative, an overreaching directional residual overcurrent measurement
element will be used as sending criterion of the permissive input signal CSOR. Also the
underreaching input signal CSUR can initiate sending.
354
AND
AND
0
50ms
AND
© Copyright 2011 ABB Power Grids. All rights reserved
0-tCoord 0
0 25ms
ANSI05000448-1-en.vsd
/Z (positive through zero-sequence
1S 0S
1MRK 506 326-UUS B
CS
TRIP
CRL
M13922-17 v5
Line distance protection REL650
Technical manual